String Builder and String Buffer in Java

Introduction

In this lesson of Java course, we will take a look at the String Builder and String Buffer in Java. Java is a popular programming language that provides developers with various features to make coding easier and more efficient. Two such features are String Builder and String Buffer. Both of these classes provide a way to manipulate and modify strings in Java, but there are differences between them that make them better suited for different scenarios.

1. String Builder and String Buffer in Java

String Builder and String Buffer are classes in Java that allow us to manipulate and modify strings. They are both part of the java.lang package and provide similar functionality, but they differ in their implementation.

1.1. String Builder

String Builder is a mutable sequence of characters that we can modify without creating a new object each time a change is made. It’s faster than String Buffer because it’s not thread-safe. This means that it doesn’t need to acquire locks to ensure thread safety.Suppose we have a StringBuilder object sb that we want to append ” Javadevjournal” to. We can use the append method like this:

StringBuilder sb = new StringBuilder("Welcome to");
sb.append(" Javadevjournal");
System.out.println(sb.toString());

Output:

Welcome to Javadevjournal

1.2. String Buffer

String Buffer is also a mutable sequence of characters that we can modify. However, it’s thread-safe, which means that it ensures that multiple threads can access the same object safely without causing data corruption or other errors.Suppose we have a StringBuffer object sb that we want to append ” Javadevjournal” to. We can use the append method like this:

StringBuffer sb = new StringBuffer("Welcome to");
sb.append(" Javadevjournal");
System.out.println(sb.toString());

Output:

Welcome to Javadevjournal

2. When to use String Builder?

We can use String Builder when we need to make a large number of modifications to a string. Because it’s not thread-safe, it’s faster than String Buffer. It’s also a good choice when we’re working with a single thread and don’t need to worry about thread safety.

3. When to use String Buffer?

We can use String Buffer when we need to ensure thread safety. If we’re working with multiple threads and need to modify a string, String Buffer is the safer choice. It’s also a good choice when we need to concatenate a large number of strings.

4. Difference between String Builder and String Buffer

FeatureString BuilderString Buffer
Thread-safetyNot thread-safeThread-safe
SynchronizationNot synchronizedSynchronized
PerformanceFaster than StringBufferSlower than StringBuilder
CapacityCan be set manually and increased automaticallyCan be set manually and increased automatically
LengthCan be changed using length() methodCan be changed using length() method
Return value of methodsReturns the modified StringBuilder objectReturns the modified StringBuffer object

Summary

String Builder and String Buffer are powerful tools for manipulating and modifying strings in Java. While they are similar, they differ in their implementation, with String Builder being faster but not thread-safe, and String Buffer being thread-safe but slower. We can choose which class to use based on our specific needs. If we need to make a large number of modifications to a string.

String Builder is a good choice. If we need to ensure thread safety, String Buffer is the better option. Both classes are useful for concatenating strings and manipulating them in various ways. By understanding the differences between String Builder and String Buffer, we can make more informed choices when working with strings in Java. You can find source code for this lesson of our GitHub repository.

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